diff options
author | Peter Hurley <peter@hurleysoftware.com> | 2013-11-22 07:16:25 -0500 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-12-04 11:05:40 -0800 |
commit | cba44dab11c8119a361d4962dc170b05012fe397 (patch) | |
tree | 25b8486c9389d8769dfd5ea5c60e89f550d749c2 | |
parent | 592ea2ae0e375a32d11b11a1d732f68c58f3fd8b (diff) |
n_tty: Fix 4096-byte canonical reads
commit c77569d2f3ef7844ee4ac7005a57da6898b302a8 upstream.
Although the maximum allowable canonical line is specified to
be 255 bytes (MAX_CANON), the practical limit has actually been
the size of the line discipline read buffer (N_TTY_BUF_SIZE == 4096).
Commit 32f13521ca68bc624ff6effc77f308a52b038bf0,
n_tty: Line copy to user buffer in canonical mode, limited the
line copy to 4095 bytes. With a completely full line discipline
read buffer and a userspace buffer > 4095, _no_ data was copied,
and the read() syscall returned 0, indicating EOF.
Fix the interval arithmetic to compute the correct number of bytes
to copy to userspace in the range [1..4096].
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/tty/n_tty.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/drivers/tty/n_tty.c b/drivers/tty/n_tty.c index 7a744b69c3d..118569f0603 100644 --- a/drivers/tty/n_tty.c +++ b/drivers/tty/n_tty.c @@ -2005,7 +2005,10 @@ static int canon_copy_from_read_buf(struct tty_struct *tty, found = 1; size = N_TTY_BUF_SIZE - tail; - n = (found + eol + size) & (N_TTY_BUF_SIZE - 1); + n = eol - tail; + if (n > 4096) + n += 4096; + n += found; c = n; if (found && read_buf(ldata, eol) == __DISABLED_CHAR) { |